You will never receive any acknowledgement from USCIS. Instead, a copy of the withdrawal letter, as well as proof of its delivery to USCIS should be brought to the consulate on your patents' next visa interview.
Their visas will be issued if they can overcome the "immigrant intent" burden found on INA 214(b) by demonstrating ”substantial ties" to their country of nationality.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
I agree with Mr. Behar. You will have to rely on proof that your aunt withdrew the I-130 and proof that your parents have significant ties to their home country so as to overcome the presumption of immigrant intent.
Attorney involvement with the visitor visa process is limited, but you may be able to work with an attorney to compile evidence of your parents' ties to their home country, their intention to return to their home country after the visit, and perhaps draft an affidavit explaining the circumstances of their case.
Good luck to you!
I, too, agree.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.